package lanqiao;

import java.util.Scanner;

public class 刷题统计 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        int n = scanner.nextInt();
        int ans = 0;
        int i =1;
        while (ans<n){
           if (0<i%7 && i%7<6){
               ans+=a;
               i++;
           }else {
               ans+=b;
               i++;
           }
        }
        System.out.println(i-1);
    }
}
